We have previously described a novel system to study HIV-1- monocyte/macrophage interactions by infecting a series of human monocyte and macrophage hybridomas with various strains of HIV-1. One of the earliest defects noted in these cell lines was their inability to support an antigen specific MHC matched T cell proliferative response. This is consistent with one of the earliest immunologic deficits described in HIV-1 infection (lack of response to specific antigens) and the fact that macrophages are infected early in the course of disease. Our preliminary data suggested that loss of antigen specific responses may in fact relate to monocyte dysfunction. In exploring the mechanisms underlying this inability to stimulate an antigen specific response, three defects were defined 1.) loss of Class II antigen expression with maintained Class I antigen expression, 2.) dysregulated cytokine production (increased IL-6 and decreased IL-1), and 3.) abnormal processing of antigen. The goal of this proposal is to characterize the defects underlying these findings and determine whether intracellular infection globally alters sorting and processing of intracellular proteins or if virus contributes to downregulation of function. We will first determine the level at which HIV-1 infection is inhibitory for Class II antigens in the macrophages hybridoma cell lines (transcription or in protein production of sorting). We will then attempt to reverse the defect with gamma-interferon, GM-CSF, and LPS treatment or transfection with full length cDNA for the Class II antigens. Co-localization studies of Class II Ag and Ag processed exogenously will be determined using this model. The effect of chronic HIV-1 infection on anti-CD-3 and PHA mediated T cell proliferation will also be studied. We will assess the effect of HIV-1 infection on TNF- alpha, GM-CSF, IL-8 and IL-1-alpha production. Levels of each cytokine will be compared in the chronically infected cell lines to the uninfected cell lines. Similar to the studies for the Class II antigens, we will determine whether the defect is transcriptional, post-transcriptional or in sorting. These studies should aid in our understanding of early immune dysfunctional in HIV-1 infection.